On Sat, 26 Jul 2008 07:09:58 -0400, John Smith wrote:
These freqs, being opened up for the net, is a very exciting developmen
t
... I believe the opportunities and access provided will greatly expand
the availability to the net under adverse circumstances, and make
greater speeds available to those who were lacking the same ...

Believe it when you see it...

BPL was promised as the way to get broadband to rural residents. Never
saw any of it deployed in rural areas - all the test systems ended up in
suburbia.

On Jul 26, 11:32�am, Doug Smith W9WI wrote:

BPL was promised as the way to get broadband to rural
residents. �Never saw any of it deployed in rural areas -
all the test systems ended up in suburbia.

AFAIK, the reason for that is the classic rural-utilities problem: how
to get a usable return on investment from a low-density customer base.
Given a reasonable rate structure, often there simply aren't enough
revenue dollars to justify the expense of installation and
maintenance.

Note that the last parts of the USA to get electricity were the rural
ones, and it took government programs like the REA and TVA to make it
happen. (See windmill/farm radio story below).

Access-BPL isn't a way to get broadband to cover more than a mile or
two; that's a job for fiber optics. Access-BPL is all about the "last
mile": getting the broadband signal into the customer's neighborhood
and premises without new wires by using the power lines. It sounds
like a good idea until the downsides are considered. Besides the
obvious interference issues, there's the need to install devices to
permit the BPL signal to bypass the distribution transformers (which
raises a whole bunch of safety concerns) and how lossy the power lines
are to the BPL signal (because it's radiating!).

Economics alone may be the doom of BPL.

---

And now the farm radio story:

Years after electric lighting and radio broadcasting were common in
the USA, many farms and rural areas did not have electricity. In some
areas, small local cooperative power systems were built, with varying
degrees of success. But in many areas the distances were so great that
such systems did not happen.

One solution that had a fair following was the windmill generator.
Windmills had long been used for pumping water - in fact the artesian
well and the water-pumping windmill were major factors in the
cultivation of the Great Plains. Companies like Wincharger produced
wind-powered electric systems for lighting. Typically these were ~32
volt DC systems with storage batteries for windless nights.

The farm folks wanted radio, too, but usually the cost of an electric
system just to power a receiver was prohibitive.

So AM BC radios were developed to run from the windmill power systems.
They used ordinary receiving tubes with the heaters in series and the
plate supply direct from the 32 volts, for economy. The resulting low
gain was dealt with by an additional stage or two and paralleled audio
output tubes. Still cheaper and less trouble than a dynamotor or
vibrator supply, and used less energy. These wind-powered radios are
rare now because they were only sold in rural areas and became
obsolete when rural electrification came through. Plus one more
factor:

One unusual feature of the 32 volt systems was that they used the same
hardware (lamp sockets, outlets, switches, wiring) as 110 volt AC
systems. This seemed like a good idea at the time because it
eliminated future re-work. But it was risky because if someone plugged
the wrong-voltage device in, there could be a lot of smoke released.
More than a few 32 volt radios met an untimely demise from such
mistakes.

Another approach stemmed from the development of low-drain 1.4 volt
filament receiving tubes. "Farm radios" designed around these tubes
and powered by dry cell batteries were developed for the rural market.
Special combination-block dry cell batteries were developed where the
cells were sized for a particular set design so that the A and B
sections wore out together. They were a staple of rural-area radio-
sales-and-repair shops until the electrification came through.

Now, 60-odd years later, we are seeing a resurgence in wind power and
off-the-grid technology. Everything old is new again.

73 de Jim, N2EY